采用SPS工艺制备添加La_2O_3或LaB_6的ZrB_2-SiC陶瓷,测量试样的密度和力学性能,利用扫描电镜和透射电镜观察试样的微观形貌,研究添加镧的不同化合物对ZrB_2-SiC陶瓷显微结构和力学性能的影响,分析添加量对材料力学性能的影响.同时对ZrB_2-SiC-La_2O_3和ZrB_2-SiC-LaB_6陶瓷进行热处理,考察热处理对其力学性能的影响.结果表明,加入2.5%或5%(质量分数, 下同)的La_2O_3或LaB_6添加剂后,材料的室温强度、高温强度、断裂韧性都比无添加剂时要高;当含量相同时,加入LaB_6比La_2O_3更有利于提高陶瓷材料的室温强度;当添加剂的含量为2.5%时,材料的室温强度比较好,当添加剂的含量为5%时,材料的高温强度和断裂韧性比较高.热处理可以提高ZrB_2-SiC-La_2O_3和ZrB_2-SiC-LaB_6陶瓷材料的高温强度.
ZrB_2-SiC ceramic composites added with La_2O_3 and LaB_6 additives were prepared by SPS process. The properties such as density, strength and fracture toughness were tested. The microstructures were observed by SEM and TEM. Both the effect of different compounds including La and the effect of the additive content on the microstructures and mechanical properties of ZrB_2-SiC ceramic composites were discussed. The effect of heat treatment on ZrB_2-SiC ceramic composites with La_2O_3/LaB_6 additives was investigated. The results show that the density, intensity at room and high temperature and fracture toughness of the ZrB_2-SiC ceramics with 2.5wt% and 5wt% La_2O_3/LaB_6 are higher than that of ZrB_2-SiC ceramics without additives. LaB_6 is better than La_2O_3 in improving the strength at room temperature when the additive content is the same. The strength at room temperature is better when the content of additive is 2.5wt%. However, the strength at high temperature and the fracture toughness are better when the additive content is 5wt%. Heat treatment can improve the strength of ZrB_2-SiC ceramic composites at high temperature.
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